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ATTORNEY United States atent 3,055,540 CONTAINER AND CLQSURE THEREFOR Arthur Ringlen, Brooklyn, N.Y., assignor to LB. Plastics Manufacturing Corpn, Yonkers, N.Y., a corporation Filed Feb. 9, 1961, Ser. No. 88,185 11 Claims. (Cl. 220-60 This invention relates in general to a container and closure therefor, and more specifically to an improved construction of a semi-rigid, open end container and closure therefor. The container to which this invention pertains is particularly adapted for use in the distribution and sale of various comestibles such as prepared salads, gelatin desserts, semi-fluids foods, stored refrigerated foods, and the like.

Many kinds of semi -fluids foods, such as salads, gelatin and the like, are currently sold and distributed in semirigid plastic packages. Such packages generally consist of a dish shaped container, in which the food stuff is packed and a closure frictionally fitted to the upper end thereof to seal the same. To facilitate storage, shipping and display of the foods so packaged, it is customary to form the closure of containers of this type with a recessed portion to permit stacking of the individual containers one on the other. Because of the relatively thin walls and the semi-rigid construction of such containers, it has been noted that the stacking of the packed containers frequently caused the seal of the container at the bottom of any such stack to be broken or separated, thus resulting in either a damaged or spoiled unit. This breaking of the seal on the lower container of a given stack is attributed to the weight of the column standing above the damaged container. It has been noted that the weight of the column or stack on a given container causes the semi-rigid closure of the given container to sag or flex inwardly. This sagging causes the edges of the closure to be pulled away from the walls of the container, thereby breaking the seal therebetween. When this occurred the contents would then become unfit for sale and therefore result in a wasted or damaged unit.

Therefore an object of this invention is to provide in a semi-rigid container an improved construction of a semi-rigid closure that is pre-formed in a manner so as to exert a positive pressure against the walls of the container in the sealing position thereof and thereby minimize the tendency of the seal formed at the junction of the closure and its container to separate.

Another object is to provide in a semi-rigid container an improved semi-rigid closure constructed and arranged to stress the walls of the container in the sealed position thereof so that an applied force tending to break the seal merely relieves the initial stress imposed on the container walls without effecting a separation or breaking of the seal formed therebetween.

Other features and advantages will become readily apparent 'when considered in view of the description and drawings in which:

FIG. 1 illustrates a stacked arrangement of the containers embodying the instant invention.

FIG. 2 is a top plan view of an individual container constructed and arranged in accordance with this invention.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2.

FIG. 4 is an enlarged detail sectional view taken along line 4-4 of FIG. 2.

FIG. Sis an enlarged detail plan view of a corner section of the closure.

FIG. 6 is a schematic plan view of a modified closure construction for use with a rectangular or oblong container, and

it 1C6 FIG. 7 is a schematic plan showing of still another modified form of the invention.

Referring to the drawings, FIG. 1 illustrates a column of stacked containers 10. Containers of the type to which this invention is directed are preferably utilized for the sale and distribution of food stuffs of various kinds. To provide stacking to facilitate storage, shipping and displaying containers of this type, the closure of each container, as will be hereinafter described, is provided with a recessed portion shaped and constructed to receive the body portion of another container.

Containers of this type are generally formed from sheets of relatively very thin material, e.g. plastic sheets having a thickness of .010, .015, .020 of an inch. Generally, the lids are fabricated from a lighter gauge plastic material than is the base. Consequently such containers are considered to be semi-rigid in construction. Thus in stacking such containers, it has been heretofore difficult to maintain a proper seal between the container and its closure located in the bottom portion of a given stack.

In accordance with this invention this difficulty is eliminated. Referring to the drawing, the container 10 of this invention comprises a body 11 having a full open end and a closure 12 therefor. Preferably these members are formed from a suitable plastic sheet material, e.g. acetate, polyethylene, polypropylene, vinyl or high impact styrene and the like having a gauge thickness of only a few thousands of an inch, eg .010, .015, .020.

While a container 10' embodying this invention may be formed as any multi-sided or polygonic shape, FIGS. 1 to 5 are illustrative of a typical square 16 oz. container.

In the illustrated embodiment the container 10 comprises a full open end body 11 having a bottom wall 1 3 and integrally connected upright oppositely disposed side walls 14 and 15, respectively. As shown, the walls are integrally connected at the corners, and each wall tapers outwardly. Formed at the upper end of each side wall 14, 15 is a laterally extending offset portion 16. Connected to the outer periphery of the ofiset portion 16 is an upright rim 17. As best seen in FIG. 3, there is formed at the junction of the rim 17 and the offset portion 16 an internal groove 18 which extends about the entire periphery of the container offset portion 16. It will be noted that the lower portion 17A of rim 17 is inclined inwardly and the upper portion 17B thereof inclines outwardly. At the junction between the upper and lower rim portion 17A, 17B, there is formed an inner shoulder 19, and the upper end of the outwardly inclined rim portion 17A terminates in a laterally extending flange 20.

In accordance with this invention it is to be noted that each side wall 14, 15 of the container is traversely extended between the corners thereof in a straight line. The closure 12 in contrast thereto, as will be herein described, is formed with oppositely disposed, outwardly bowed or arcuate curved wall portions 22.

As best seen in FIGS. 2 to 4, the closure 12 for container 10 is formed with a central recessed or bottom wall 21 adapted to receive the bottom Wall 13 of a similar container 10. Integrally formed with the recessed portion 21 of the closure 12 is a circumscribing upright side wall 22. At the junction of the side wall 22 and recessed bottom wall 21 there is formed an outwardly projecting bead 23 which is adapted to register with groove 18 in the sealed position of the closure 12. Also the upright side walls 22 of the closure 12 are formed with an inwardly inclined lower portion 22A and an outwardly inclined upper portion 22B with shoulder 24 formed therebetween. The upper end of the side Wall 22 terminates in a flange 25 adapted to overlie flange 20 of the container 10 in the operative sealed position. If desired a reinforcing groove 26 may be provided in the bottom wall to stiffen the same.

A feature of this invention resides in the provision that the opposed side Walls 22 of the closure 12 are preformed so as to be bowed outwardly. As shown in FIG. 2, each side wall 22 of the closure is arcuately formed to define an are having a radius R. By way of example it will be observed that for a closure 12 having a gauge thickness of .010 inch and a width D of approximately 5.8 inches, the radius of curvature R equals approximately ten (10) feet.

Therefore in accordance with this invention it will be noted that when the closure 12, as described, is fitted to the container 11 so that with the closure 12 seated on the offset portion 16, the arcuate or bowed side walls 22 of the closure will exert a positive sealing pressure against the complementary rim portions 17 of the container. The action between the curved side walls 22 of the closure and the straight mating rim 17 of the container is one of tension and compression. That is, the curved portion of the closure side walls 22 will stress the rim 17 of the container in tension, and the reaction of the rim 17 on the side walls 22 of the closure is in compression. The curved side walls 22 of the closure exert pressure on the side wall of the container extending from a maximum at the center (see FIGS. 2 to 4) to the corners and as a result create a compressive force which maintains pressure of the corners of the container against the corners of the closure. The compressive force exerted on the curved side walls 22 of the closure tends to straighten the same thus forcing the corners of the closure into tight engagement with the corner of the container. Consequently, a positive sealing force is had between a container 11 and its closure 12 in accordance with this invention. For this reason a container closure, of the type herein described, is able to Withstand a greater Weight. This means that the seals on the lower containers of any given stack are not likely to separate, and thus much less spoilage or Waste can be expected with the inventive concept herein described, under a given set of conditions.

In effect, the closure 12 formed in accordance with this invention in effect pre-stresses the walls or rim of the container when the closure is snapped in sealing position. Thus when a weight or force is applied to the closure 12 and the closure tends to sag inwardly of the container, the effect thereof is merely that of relieving the pre-stress of the container, rather than in a pulling away or separation of the closure wall portions 22 from the rim 17 of the container. The relieving of the stress in the rim of the container in turn effects a compressive force in the side walls 22 of the closure which exerts a pressure at the corners to effect a locking force thereat. Thus a more positive seal can be effected between the container and its closure.

FIGS. 6 and 7 illustrate schematic showings of modified embodiments 28, 29, respectively, of the invention. In these forms the invention is applied to a rectangular or oblong shaped container, and the details of construction thereof are similar to that described with reference to FIGS. 1 to with the exception of shape. Depending on the width of the respective forms of the modified embodiment either the long sides 30 only of the embodiment 28 are bowed, or both long sides 32 and short sides 33 of embodiment 29 are bowed.

While the instant invention has been disclosed with reference to a particular embodiment thereof, it is to be appreciated that the invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

1. In combination, an open end semi-rigid container having polygonically arranged and oppositely disposed side walls, each of said walls having a lateral offset with a connected upright rim rectilinear in horizontal crosssection extending therealong, and a semi-rigid closure for said container, said closure having a recessed bottom and connected upright closure walls, said bottom adapted to seat on said lateral offset with said closure walls engaging said rim, said closure having opposed wall portions that are outwardly bowed so as to exert a positive pressure against the rectilinear rim of said container in engagement therewith, the reaction of which exerts a compression force toward the corners of the container to form a positive seal thereat.

2. In combination, an open end, semi-rigid container having oppositely disposed side walls, each of said walls having a lateral offset and a connected upright rectilinear rim segment in horizontal cross-section extending therealong, and a closure for sealing said open end, said closure being formed of a material having a gauge thickness less than that of the container, and said closure having a recessed bottom and connected upright opposed closure walls, said bottom when in sealing position adapted to seat on said offset with the opposed closure walls in respective engagement with said rim segments, and an opposed pair of said closure walls having an outwardly bowed portion to exert a positive sealing pressure against the rectilinear rim of said container in prestressing the latter whereby the reaction of said rim on said outwardly bowed closure walls exerts a compressive force therebetween upon the flexing of said outwardly bowed closure walls to form a positive seal thereat.

3. In combination, an open end, semi-rigid container having rectangularly disposed side walls, each of said walls having a lateral extending flange terminating in a connected upright rim segment extending therealong, each of said rim sections being rectilinear in cross-section, and a rectangular semi-rigid closure for sealing said open end, said closure having a recessed bottom portion having integrally connected upright opposed closure walls, said bottom portion when in sealing position adapted to seat on said flange with the opposed closure walls in respective engagement with the rectilinear extending rim segments of the respective side walls of said container, and the opposed closure walls having an outwardly bowed portion to exert a positive sealing pressure against the rim of said container whereby the reaction of said rim on said outwardly bowed closure walls exerts a compressive force on said closure toward the corners of said container upon the flexing of said outwardly bowed closure walls to form a positive seal thereat.

4. In combination, an open end semi-rigid container having poly-gonally disposed side walls, each of said side walls having an outwardly turned flange and an upright rim rectilinear in horizontal cross-section connected to the outer periphery of said flange, said rim being integrally connected with said flange, and internal groove formed at the junction of said flange and connected rim, and a semirigid closure for sealing said open end the material of said closure having a gauge thickness less than that of said container, said closure having a recessed bottom portion adapted to seat on the flange of said container, polygonally disposed upright closure walls integrally connected to said bottom, each said closure walls being adapted to engage with said rims, and said closure walls forming with said bottom at the juncture therebetween an outwardly projecting bead which is adapted to snap in said groove, the opposed walls of said closure being slightly bowed outwardly so that when said closure is seated on said flange and the walls of said closure fitted to said rim, the outwardly bowed closure walls acting on said rectilinear rims cooperate to exert a positive compressive force therebetween to insure a proper sealing force therebetween, and the reaction of said rims on said bowed closure walls tends to flex said outwardly bowed closure walls upwardly of the container to enhance the pressure exerted at the corners of said container.

5. An open end, semi-rigid container having upwardly extending rectangular disposed side walls, each of said side walls having an outwardly extending offset, and upwardly extending rim integrally connected to the outer periphery of said offset, said rim being rectilinear in horizontal cross-section said rim and offset forming at the junction thereof an internal groove, a semi-rigid closure adapted to seal said open end, said closure having a recessed bottom portion having integrally connected upright rectangular disposed closure walls, said closure walls and bottom portion forming at the junction thereof a bead which is adapted to snap in said groove, and said closures having a pair of opposed walls that are outwardly bowed so that when said closure is seated on said lateral offset, the outwardly bowed closure wall acting on said rim effects a positive sealing force therebetween.

6. The invention as defined in claim 5 wherein the rectangular disposed walls of said container and closure therefor are equilateral.

7. The invention as defined in claim 5 wherein each of said closure side walls are outwardly bowed.

8. The invention as defined in claim 5 wherein only the longer of the closure side walls are outwardly bowed.

9. An open end, semi-rigid container having upwardly extending rectangular disposed side walls, each of said side walls having an outwardly extending offset and upwardly extending rim rectilinear in horizontal cross-section integrally connected to the outer periphery of said offset, said rim and offset forming at the junction thereof an internal groove, said rim having an inwardly inclined lower portion, an outwardly inclined upper portion terminating in a laterally extending flange, an internal shoulder formed at the juncture of said upper and lower portions of said rim, a semi-rigid closure adapted to seal said open end, said closure having a recessed bottom portion having integrally connected upright rectangular disposed closure walls, said closure walls and bottom portion forming at the junction thereof a bead which is adapted to snap in said groove, said closure walls having a cross sectional contour complementing that of said rim, and said closures having a pair of opposed walls that are outwardly bowed so that when said closure is seated on said lateral offset, the outwardly bowed closure wall acting on said rim effects a positive sealing force therebetween.

10. An open end, semi-rigid container having oppositely disposed side walls, each of said side walls having a lateral offset and an upright rim segment rectilinear in horizontal cross-section connected thereto, and a closure for sealing said open end, said closure having a recessed bottom and connected upright opposed closure walls, said recessed bottom when in sealing position adapted to seat on said offset with the opposed walls of said closure in respective engagement with the rim segments, said side walls and closure walls having cooperating mating surfaces that are complementing in cross-section, and an opposed pair of said closure walls having an outwardly bowed portion for exerting a positive sealing pressure against the rim of said container whereby the reaction of said rim on said outwardly bowed closure walls exerts a compressive force toward the corners of said container to form a positive seal thereat.

11. An open end, semi-rigid plastic rectangular container and closure therefor, said container having a bottom wall and connected upwardly extending side walls integrally formed thereto, each of said side walls having an outwardly extending offset portion, an upwardly extending straight rim rectilinear in horizontal cross-section integrally connected to the outer periphery of said offset portion, said rim and ofiset defining at the junction thereof a circumscribing internal groove, said rim having an inwardly inclined lower portion and a connected outwardly inclined upper portion, an internal shoulder formed at the junction of said upper and lower rim portions, and said upper portion terminating in an outwardly turned flange, said closure for sealing said open end having a recessed bottom portion and integrally connected rectangular disposed side wall portions, an outwardly projecting bead formed at the junction between said side wall portions and bottom portion of said closure whereby said bead is adapted to snap in said groove when the closure is seated on said offset of the container side walls, each of said closure side wall portions having an inwardly inclined lower portion, an outwardly inclined upper portion, an external shoulder formed at the junc tion therebetween and a laterally extending flange connected to the upper portion of said closure side wall portion, and a pair of the closure side wall portions being arcuately bowed outwardly so that when the closure is seated on said offset, the outwardly bowed closure side wall portion acting on the complementary straight portions of said rim effect a positive seal between said closure and rim of said container.

References Cited in the file of this patent UNITED STATES PATENTS 1,685,765 Maugan Sept. 25, 1928 2,941,562 Ripin June 21, 1960 2,947,463 Conklin Aug. 2, 1960 2,975,931 Harrison Mar. 21, 1961 

